The present invention relates to a tissue separation dissector used for forming an elongated cavity in subcutaneous tissue, particularly along the course of a small blood vessel. More specifically, this invention relates to an endoscope-covering sheath used for endoscopic blood vessel harvesting which endoscopically harvests a subcutaneous blood vessel such as the great saphenous vein.
Surgical methods and endoscopic dissectors for dissecting and harvesting a subcutaneous blood vessel such as a great saphenous vein are known in, for example, U.S. Pat. Nos. 7,077,803; 6,863,674; 6,432,044; and 5,895,353, incorporated by reference in their entirety. The dissector is a straight tubular device with an internal instrument insertion passage and a handle portion provided at the proximal end of the dissector. A rigid endoscope is introduced in the instrument insertion passage of the dissector from the end of the handle portion.
When a subcutaneous blood vessel, such as a great saphenous vein, is to be endoscopically dissected by using the dissector, a surgical method such as demonstrated by FIG. 21 is utilized. The entire length of a target blood vessel C extending from the upper portion of the inguinal region A of the thigh of a lower limb 1000 to the ankle B is desired to be removed. The medical professional (i.e., the operator) performs a skin incision E2 at the knee area D, for example, immediately above the blood vessel C by means of a scalpel or the like. The operator exposes the blood vessel C in the area of the skin incision E2 by means of blunt dissection or the like. The operator parts tissue immediately above the blood vessel C by means of a dissector over a distance from a portion of skin E2 such that the blood vessel is observable to the naked eyes. Once the vessel is fully dissected from the surrounding tissue, small incisions (herein after referred to as stab wounds) are performed distal to the knee incision (e.g., at inguinal position E1 and ankle position E3) and blood vessel C is extracted through incision E2.
FIG. 22 shows a cross-sectional view taken along line 22-22 of FIG. 21. Reference numeral 1001 denotes skin, reference numeral 1002 denotes a subcutaneous tissue, and reference numeral 1003 denotes a connective tissue overlying and surrounding blood vessel C. In a dissecting operation, the operator first uses a dissector rod having a blunt conical tip to form a cavity G between the surrounding tissue and blood vessel C. Blood vessel C is isolated from the surrounding connective tissue 1003 anteriorly, posteriorly, laterally, and medially as much as possible using the dissector rod. Following blunt dissection from connective tissue 1003, blood vessel C continues to be connected to the body of the patient by side branches F of the vessel and by remaining bits of connective tissue.
In order to harvest blood vessel C, the side branches F and remaining connective tissue between the incised portions of skin E2 at knee D and inguinal region A must be removed. Thus, the operator removes the dissector rod and inserts a harvesting tool into cavity G through incised portion of skin E2. The harvester includes a keeper (i.e., loop) for slidably receiving vessel C. The operator progressively slides the tip of the harvester from incision E2 alternately toward the incised portions of skin E1 and E3 along an outer surface of blood vessel C while observing through the rigid endoscope loaded into the interior of the harvester and cutting through side branches F and remaining connective tissue using a cutter (i.e., forceps) that is integral with the keeper. In the course of the cutting operation within cavity G, the operator moves the harvester device back and forth while cutting (e.g., cauterizing) branches by manipulating a set of controls disposed at the proximal end of the harvester. An insufflation gas (e.g., CO2) is introduced into cavity G through the tip of both the dissector rod and the harvester rod to hold open cavity G and maintaining separation between vessel C and the surrounding subcutaneous tissue 1002 and connective tissue 1003.
During initial dissection of cavity G (referred to as the first pass), the dissector encounters high resistance so that the operator must manually apply a strong force to move forward. The resistance is due to the blood vessel C, the connective tissue 1003 and the subcutaneous tissue 1002 being connected tightly together. The prior art has suffered from operator fatigue and inefficient performance of the dissection/harvesting operation.